ABSTRACT The oblique wave scattering by fully-extended two-layered, three-layered and submerged two-layered porous structures occupying finite width is reported using an analytical model based on the eigenfunction expansion method. The fully extended two-layered structure is composed of two porosities and friction factors in the surface porous layer and the bottom porous layer. In addition, the three-layered energy-absorbing structure is composed of two-porous layers along with the bottom rigid layer to replace the natural seabed variation. Further, the study is extended for multiple energy-absorbing structures to report the impact of free spacing available between the two subsequent structures on fluid resonance. The two-layered porous structure dispersion relation is derived and solved using step approach and Newton-Raphson method. The derived analytical results are validated with the published results of notable authors. The effect of the surface and bottom layers porosity, friction factor, free spacing, structural width, number of structures, and angle of contact on the wave scattering is reported. Finally, the comparative study between the single and multiple energy absorbing structures of multiple horizontal layers is discussed. Further, the significance of the critical angle of contact and fluid resonance for better wave blocking is presented precisely, which is essential for the coastal engineers to design offshore structures.

中文翻译：

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可变水平孔隙度多吸能结构的表面重力波散射

摘要 利用基于特征函数展开法的解析模型，报告了占据有限宽度的完全扩展的两层、三层和浸没式两层多孔结构的斜波散射。完全延伸的两层结构由表面多孔层和底部多孔层中的两个孔隙率和摩擦系数组成。此外，三层吸能结构由两孔层和底部刚性层组成，以取代天然海床变化。此外，该研究扩展到多个能量吸收结构，以报告两个后续结构之间可用的自由间距对流体共振的影响。采用阶梯法和Newton-Raphson方法推导并求解了两层多孔结构色散关系。派生的分析结果与著名作者发表的结果进行了验证。报告了表层和底层孔隙率、摩擦系数、自由间距、结构宽度、结构数量和接触角对波散射的影响。最后，讨论了多水平层单吸能结构与多吸能结构的对比研究。此外，临界接触角和流体共振对于更好地阻挡波浪的重要性得到了精确呈现，这对于沿海工程师设计海上结构至关重要。并且报告了波散射的接触角。最后，讨论了多水平层单吸能结构与多吸能结构的对比研究。此外，临界接触角和流体共振对于更好地阻挡波浪的重要性得到了精确呈现，这对于沿海工程师设计海上结构至关重要。并且报告了波散射的接触角。最后，讨论了多水平层单吸能结构与多吸能结构的对比研究。此外，临界接触角和流体共振对于更好地阻挡波浪的重要性得到了精确呈现，这对于沿海工程师设计海上结构至关重要。